KR100200860B1 - Method and device for dubbing hifi audio signal - Google Patents

Abstract

The present invention relates to a copying apparatus for reproducing and recording a high-fidelity audio signal recorded on a video tape to another video tape, and more particularly, to a new recording method and apparatus suitable for preventing signal degradation.

A method of copying a hi-fi audio signal according to the present invention is characterized in that an FM audio signal reproduced through a reproduction head is provided to a recording head without a demodulation and modulation device.

In the copying method according to the present invention, the FM audio signal reproduced by the reproducing head is directly applied to the recording head for recording, thereby having the effect of preventing the signal from being degraded by switching operation, demodulation and modulation.

Description

Hi-Fi audio signal copying method and apparatus suitable for this

1 is a diagram showing the configuration of an audio signal reproducing unit in a conventional hi-fi copy apparatus.

FIG. 2 is a diagram showing the relationship between the head switching pulse and the FM audio signal in the apparatus shown in FIG.

3 is a diagram showing the configuration of an audio signal recording unit in a conventional hi-fi copy apparatus.

4 is a diagram showing the configuration of a hi-fi copying apparatus according to the present invention.

5 is a diagram showing a spectrum of an FM audio signal.

The present invention relates to a copying apparatus for reproducing high-fidelity audio signals recorded on a videotape and recording them on another videotape. More particularly, the present invention relates to a novel recording method and apparatus suitable for preventing the deterioration of a signal.

A high fidelity audio signal copying apparatus is a device that reproduces an FM (Frequency Modulation) audio signal recorded deeply on a video tape and records it on another video tape.

A conventional hi-fi audio signal copying apparatus includes an audio signal reproducing unit for reproducing an audio signal from an FM audio signal reproduced through a reproducing head, and a recording unit for FM modulating the audio signal provided from the audio signal reproducing unit and providing it to the recording head. It was.

The FM audio signal input to the audio signal reproducing unit is an FM audio signal provided from two reproduction heads multiplexed by a head switching pulse.

In addition, the FM audio signal applied to the recording head is one in which the signal provided from the audio signal reproducing unit is demultiplexed by the head switching pulse.

Therefore, the conventional hi-fi audio signal copying apparatus cannot avoid the influence of the noise introduced in the multiplexing and demultiplexing operations by the head switching pulses.

In addition, there is a problem that signal degradation due to demodulation and modulation cannot be avoided.

Accordingly, an object of the present invention is to provide a novel copying method for preventing a deterioration of a signal that may be generated during copying as created to solve the above problems.

Another object of the present invention is to provide an apparatus suitable for the above copying method.

A method of copying a hi-fi audio signal according to the present invention for achieving the above object is

A method of copying a hi-fi audio signal for recording an FM audio signal reproduced through a reproduction head through a recording head,

And the FM audio signal reproduced through the reproduction head is provided to the recording head without interposing the wood and the modulation device.

According to another aspect of the present invention, there is provided a radiation apparatus for a hi-fi audio signal.

A copying apparatus of a hi-fi audio signal for recording an FM audio signal reproduced through a reproducing head through a reproducing head,

And a transmission line for directly providing the FM audio signal output from the reproduction head to the recording head. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the configuration of a playback section in a conventional apparatus for copying hi-fi audio signals. The reproducing section shown in FIG. 1 has reproducing heads CH11 and CH12 for reproducing the hi-fi audio signal recorded deeply on the tape, and RM audio signals reproduced through the reproducing heads CH11 and CH12 controlled by the head switching pulses. The FM audio signal processed by the switch SW1 for multiplexing and a preamplifier for amplifying the FM audio signal provided from the switch SW1 is input.

The FM audio signal is separated into L and R channel FM audio signals by band pass filters BPF1 and BPF2 of 1.3 MHz and 1.7 MHz. The separated signal is demodulated as a speech signal in the demodulation circuits DEMOD1 and DEMOD2. The demodulated speech signal is corrected by the inverse characteristics of pre-emphasis during recording via the de-emphasis circuits DE-EMPHA1 and DE-EMPHA2. Otherwise, unnecessary noise is removed from the low pass filters LPF1 and LPF2 and provided as audio outputs L and R. At this time, the quality of the reproduced audio outputs L and R tends to deteriorate rather than that at the time of recording according to the processing of the reproducing section.

2 shows the relationship between the head switching pulse and the FM audio signal in the switch shown in FIG. The switch SW1 is controlled by the head switching pulse HD-SW1 to selectively output the FM audio signal provided from CH11 or CH12. (The head switching pulse is well known and thus detailed description thereof is omitted.)

At this time, spike-shaped switching noise is generated at the portions (point A and point B) that are switched by the switching operation of the switch SW1, which is introduced into the reproduced FM audio signal. This adversely affects the quality of the audio signal and should be removed.

3 shows the configuration of a recording unit in a conventional apparatus for copying hi-fi audio signals. The L and R voice signals are prevented from deterioration of the S / N ratio due to the triangular noise generated during FM recording / playback through the tri-emphasis circuits PRE-EMPHA1 and PRE-EMPHA2. Walk through the pre-emphasis to emphasize the highs. Next, amplitude limitation is performed through the limiters LIM1 and LIM2 to prevent overmodulation by the pre-emphasis process.

The L-channel voice signal is then FM-modulated at 1.3 MHz ± 50 KHz and the R-channel voice signal at 1.7 MHz ± 50 KHz (for NTSC) through the modulation circuits MOD1 and MOD2, and the area pass filter (LPF1, LPF2) Is synthesized by the synthesizer ADD and provided to the recording heads CH21 and CH22. At this time, the quality of the recorded FM audio signal deteriorates rather than that at the time of recording according to the processing of the recording unit.

Even during recording, the recording heads CH21 and CH22 are demultiplexed through the switch SW2 controlled by the head switching pulse HD-SW2, respectively.

At this time, a spike-shaped switching noise is generated by the switching operation of the switch SW2, which is introduced into the recorded FM audio signal. This adversely affects the quality of the audio signal and should be removed.

In the recording method according to the present invention, the recording head is provided with the FM audio signal reproduced by the reproduction head as it is. As a result, signal degradation caused by the switches, reproducing units, and recording units shown in FIGS. 1 and 3 is fundamentally prevented.

Here, since the amplitude of the reproduced FM audio signal may vary depending on the preservation state of the tape, a normal amplitude limiting process can be performed to improve this.

In addition, since jitter may occur due to time variation of the traveling system during reproduction, a normal time axis correction process may be performed.

4 shows a high fidelity audio signal copying apparatus according to the present invention. In Fig. 4, reference numeral 40 denotes a tape on which a hi-fi audio signal is recorded, 42a and 42b denotes a hi-fi audio signal reproduction head, 44 denotes a rotary transformer, and 46a and 46b denote a reproduction preamplifier.

And 48a and 48b represent a limiter part.

50a and 50b denote recording preamplifiers, 52 denote rotary transformers, 54a and 54b denote high-fidelity audio signal recording heads, and 56 denote tapes on which hi-fi audio signals are to be recorded.

58 denotes a synthesizer for synthesizing and outputting the signal processed by the reproduction preamplifiers 46a and 46b. 60 denotes a synthesizer for processing the signal provided by the synthesizer 58 to demodulate the audio signal or to process the audio signal to be recorded. A hi-fi audio processor for generating an FM audio signal, 62 is a battery amplifier for amplifying the FM audio signal generated by the hi-fi audio processor 60 to be recorded on the first tape 40, and 64 is a first tape 40 Selection switch to select recording and playback.

The first limiter unit 48a is for processing the FM audio signal reproduced by the first playback head 42a, and the band pass filters 60a and 60b of the L and R channels, and the limiters of the L and R channels ( 62a, 62b), local pass filters 64a, 64b of the L channel and the R channel, and the first synthesizer 66.

The second limiter portion 48b is for processing the FM audio signal reproduced by the second reproduction head 42b, and the band pass filters 70a and 70b for the L and R channels, and the limiter for the L and R channels ( 72a, 72b), low-pass filters 74a, 74b of the L channel and the R channel, and a second synthesizer 76.

The device shown in FIG. 4 is characterized by the absence of a switch operated by a head switching pulse as compared to the device shown in FIGS. 1 and 3.

And a first limiter portion and a second limiter portion for amplitude-limiting processing of the FM audio signals reproduced from the first and second reproduction heads.

The operation of the apparatus shown in FIG. 4 will be described in detail. The FM audio signal recorded on the tape 40 is reproduced by the reproduction heads 42a and 42b. The spectrum of the FM audio signal output from the reproduction heads 42a and 42b is shown in FIG. In the hi-fi scheme, in order to separate the L and R audio signals, the L channel audio signal is modulated at 1.3 MHz and the R channel audio signal is set at 1.7 MHz as the center frequency. have.

The FM audio signal output from the reproduction heads 42a and 42b is provided to the limiter portions 48a and 48b via the preamps 46a and 46b. In a conventional reproducing unit, the FM audio signal output from the reproducing head is multiplexed through a switch controlled by the head switching signal, and amplified using a single preamplifier, but the apparatus of the present invention has no switch, and instead of the reproducing head Inherent preamps 46a and 46b are provided corresponding to 42a and 42b.

The limiter parts 48a and 48b are provided corresponding to the reproduction heads 42a and 42b, respectively. Since the reproduction heads 42a and 42b alternately reproduce the signals recorded on the tape 40, a corresponding limiter portion must be provided for each.

In addition, since the FM audio signal reproduced from the tape 40 has audio signals of the L channel and the R channel together, each of the limiter units 48a and 48b receives audio signals of the L channel and the R channel in order to efficiently process them. A band pass filter, a limiter, and a low pass filter to be processed are both provided.

Since each of the limiter parts 48a and 48b performs the same operation, only the operation of the first limiter 48a will be described.

The first band pass filter 60a is provided for extracting the L-channel audio signal. As shown in FIG. 5, since the L-channel audio signal is modulated at 1.3 MHz ± 50 KHz, the first band pass filter 60a is designed to have a suitable band pass characteristic. The L-channel audio signal output from the first band pass filter 60a is amplitude limited via the first limiter 62a and is provided to the synthesizer 66 after the noise is removed through the first low pass filter 64a. . The first low pass filter 64a is designed to have a maximum shift frequency of the L channel audio signal.

The second band pass filter 60b is provided for extracting the audio signal of the R channel. As shown in FIG. 5, since the audio signal of the R channel is modulated at 1.7 MHz ± 50 KHz, the second band pass filter 60b is designed to have a suitable band pass characteristic. The L-channel audio signal output from the first band pass filter 60a is amplitude limited via the second limiter 62b and provided to the synthesizer 66 after the noise is removed through the second low pass filter 64b. . The second low pass filter 64b is designed to have the maximum shift frequency of the R channel audio signal as the cutoff frequency.

The synthesizer 66 synthesizes and outputs the L channel audio signal and the R channel audio signal provided from the low pass filters 64a and 65b, respectively.

The FM audio signals output from the limiter sections 48a and 48b are provided to the recording preamplifiers 50a and 50b, respectively.

While a conventional recording unit amplifies using a single preamplifier and demultiplexes the FM audio signal through a switch controlled by the head switching signal, the recording head is provided to the recording head. However, the apparatus of the present invention provides two preamps 46a and 46b. Amplify using) and no switch.

The FM audio signal amplified through the preamplifiers 50a and 50b is provided to the recording heads 54a and 54b through the rotary transformer 52 and recorded in depth on the tape 56.

The apparatus shown in FIG. 4 can be applied to an apparatus for copying at a speed higher than the normal normal reproduction and recording speed. In the current technical situation, a double speed copying apparatus has been put into practical use, and there is room for further development of a faster copying apparatus in the future. Accordingly, the apparatus of the present invention can be utilized more effectively.

The synthesizer 58 synthesizes and outputs the signal processed by the reproduction preamplifiers 46a and 46b. The hi-fi audio processor 60 demodulates and outputs the audio signals L and R of the left and right channels from the FM audio signal provided from the synthesizer 58. This allows monitoring of the hi-fi audio signal during copying.

As described above, the copying method according to the present invention has the effect of not being affected by noise that may be generated during the switching operation by directly applying and recording the FM audio signal reproduced by the reproduction head to the recording head.

In addition, as in the conventional copying apparatus, the signal can be prevented from being degraded by demodulation and modulation.

Claims (14)

A method of copying a hi-fi audio signal for recording an FM audio signal reproduced through a reproducing head through a reproducing head, comprising: providing an FM audio signal reproduced through the reproducing head to the recording head without a demodulation and modulation device; A method of copying a hi-fi audio signal, characterized in that. The method of copying a hi-fi audio signal according to claim 1, further comprising a step of performing amplitude limitation processing on the FM audio signal reproduced through said reproduction head. The method of copying a hi-fi audio signal according to claim 1, further comprising: performing a time axis correction process on the FM audio signal reproduced through the reproduction head. A method of copying a hi-fi audio signal for recording an FM audio signal reproduced through a reproduction head through a recording head, the method comprising: a transmission line for directly supplying the FM audio signal output from the reproduction head to the recording head Hi-Fi audio signal copy device. The apparatus of claim 4, further comprising a limiter unit interposed on the transmission line and suppressing a level variation of the FM audio signal output from the reproduction head. 6. The apparatus of claim 5, wherein the limiter comprises: an L channel limiter for suppressing a level variation of the L channel FM audio signal included in the FM audio signal output from the reproduction head; An R channel limiter for suppressing a level variation of an R channel FM audio signal included in the FM audio signal output from the reproduction head; And a synthesizer for synthesizing the outputs of the L channel limiter and the R channel limiter and providing them to the playhead. 7. The apparatus of claim 6, wherein the limiter comprises: an L channel band pass filter for filtering the L channel FM audio signal from the FM audio signal output from the reproduction head and providing the L channel FM audio signal to the L channel limiter; And an R channel band pass filter for filtering the R channel FM audio signal from the FM audio signal output from the reproduction head and providing the R channel FM audio signal to the R channel limiter. 8. The apparatus of claim 7, wherein the limiter comprises: an L-channel low pass filter interposed between the L-channel limiter and the synthesizer, wherein a maximum shift frequency of the L-channel audio signal is a cutoff frequency; And an R-channel low pass filter interposed between the R-channel limiter and the synthesis unit and having a maximum shifted frequency of the R-channel audio signal as a cutoff frequency. 5. The apparatus of claim 4, wherein the reproducing head reproduces the FM audio signal recorded on the first tape, and the recording head records the FM audio signal on the second tape. 10. The apparatus of claim 9, wherein the first tape and the second tape are driven at a speed faster than a normal playback and recording speed. 12. The apparatus of claim 10, wherein the first tape and the second tape are driven at a speed twice as fast as the normal playback and recording speed. The apparatus of claim 4, further comprising a hi-fi audio processor for demodulating and outputting an audio signal from the FM audio signal output from the reproduction head. A copying apparatus of a hi-fi audio signal for recording an FM audio signal reproduced from a first tape traveling at a speed higher than a normal reproduction speed to a second tape traveling equally, wherein the FM audio signal output from the reproduction head is output. And a transmission line for providing the signal directly to the recording head. 15. The apparatus of claim 13, wherein the first tape and the second tape are driven at a correct speed twice the normal reproduction and recording speed.